1#ifndef _LINUX_ELEVATOR_H
2#define _LINUX_ELEVATOR_H
3
4typedef int (elevator_merge_fn) (request_queue_t *, struct request **,
5				 struct bio *);
6
7typedef void (elevator_merge_req_fn) (request_queue_t *, struct request *, struct request *);
8
9typedef void (elevator_merged_fn) (request_queue_t *, struct request *);
10
11typedef int (elevator_dispatch_fn) (request_queue_t *, int);
12
13typedef void (elevator_add_req_fn) (request_queue_t *, struct request *);
14typedef int (elevator_queue_empty_fn) (request_queue_t *);
15typedef struct request *(elevator_request_list_fn) (request_queue_t *, struct request *);
16typedef void (elevator_completed_req_fn) (request_queue_t *, struct request *);
17typedef int (elevator_may_queue_fn) (request_queue_t *, int, struct bio *);
18
19typedef int (elevator_set_req_fn) (request_queue_t *, struct request *, struct bio *, gfp_t);
20typedef void (elevator_put_req_fn) (request_queue_t *, struct request *);
21typedef void (elevator_activate_req_fn) (request_queue_t *, struct request *);
22typedef void (elevator_deactivate_req_fn) (request_queue_t *, struct request *);
23
24typedef void *(elevator_init_fn) (request_queue_t *, elevator_t *);
25typedef void (elevator_exit_fn) (elevator_t *);
26
27struct elevator_ops
28{
29	elevator_merge_fn *elevator_merge_fn;
30	elevator_merged_fn *elevator_merged_fn;
31	elevator_merge_req_fn *elevator_merge_req_fn;
32
33	elevator_dispatch_fn *elevator_dispatch_fn;
34	elevator_add_req_fn *elevator_add_req_fn;
35	elevator_activate_req_fn *elevator_activate_req_fn;
36	elevator_deactivate_req_fn *elevator_deactivate_req_fn;
37
38	elevator_queue_empty_fn *elevator_queue_empty_fn;
39	elevator_completed_req_fn *elevator_completed_req_fn;
40
41	elevator_request_list_fn *elevator_former_req_fn;
42	elevator_request_list_fn *elevator_latter_req_fn;
43
44	elevator_set_req_fn *elevator_set_req_fn;
45	elevator_put_req_fn *elevator_put_req_fn;
46
47	elevator_may_queue_fn *elevator_may_queue_fn;
48
49	elevator_init_fn *elevator_init_fn;
50	elevator_exit_fn *elevator_exit_fn;
51	void (*trim)(struct io_context *);
52};
53
54#define ELV_NAME_MAX	(16)
55
56struct elv_fs_entry {
57	struct attribute attr;
58	ssize_t (*show)(elevator_t *, char *);
59	ssize_t (*store)(elevator_t *, const char *, size_t);
60};
61
62/*
63 * identifies an elevator type, such as AS or deadline
64 */
65struct elevator_type
66{
67	struct list_head list;
68	struct elevator_ops ops;
69	struct elevator_type *elevator_type;
70	struct elv_fs_entry *elevator_attrs;
71	char elevator_name[ELV_NAME_MAX];
72	struct module *elevator_owner;
73};
74
75/*
76 * each queue has an elevator_queue associated with it
77 */
78struct elevator_queue
79{
80	struct elevator_ops *ops;
81	void *elevator_data;
82	struct kobject kobj;
83	struct elevator_type *elevator_type;
84	struct mutex sysfs_lock;
85};
86
87/*
88 * block elevator interface
89 */
90extern void elv_dispatch_sort(request_queue_t *, struct request *);
91extern void elv_add_request(request_queue_t *, struct request *, int, int);
92extern void __elv_add_request(request_queue_t *, struct request *, int, int);
93extern void elv_insert(request_queue_t *, struct request *, int);
94extern int elv_merge(request_queue_t *, struct request **, struct bio *);
95extern void elv_merge_requests(request_queue_t *, struct request *,
96			       struct request *);
97extern void elv_merged_request(request_queue_t *, struct request *);
98extern void elv_dequeue_request(request_queue_t *, struct request *);
99extern void elv_requeue_request(request_queue_t *, struct request *);
100extern int elv_queue_empty(request_queue_t *);
101extern struct request *elv_next_request(struct request_queue *q);
102extern struct request *elv_former_request(request_queue_t *, struct request *);
103extern struct request *elv_latter_request(request_queue_t *, struct request *);
104extern int elv_register_queue(request_queue_t *q);
105extern void elv_unregister_queue(request_queue_t *q);
106extern int elv_may_queue(request_queue_t *, int, struct bio *);
107extern void elv_completed_request(request_queue_t *, struct request *);
108extern int elv_set_request(request_queue_t *, struct request *, struct bio *, gfp_t);
109extern void elv_put_request(request_queue_t *, struct request *);
110
111/*
112 * io scheduler registration
113 */
114extern int elv_register(struct elevator_type *);
115extern void elv_unregister(struct elevator_type *);
116
117/*
118 * io scheduler sysfs switching
119 */
120extern ssize_t elv_iosched_show(request_queue_t *, char *);
121extern ssize_t elv_iosched_store(request_queue_t *, const char *, size_t);
122
123extern int elevator_init(request_queue_t *, char *);
124extern void elevator_exit(elevator_t *);
125extern int elv_rq_merge_ok(struct request *, struct bio *);
126
127/*
128 * Return values from elevator merger
129 */
130#define ELEVATOR_NO_MERGE	0
131#define ELEVATOR_FRONT_MERGE	1
132#define ELEVATOR_BACK_MERGE	2
133
134/*
135 * Insertion selection
136 */
137#define ELEVATOR_INSERT_FRONT	1
138#define ELEVATOR_INSERT_BACK	2
139#define ELEVATOR_INSERT_SORT	3
140#define ELEVATOR_INSERT_REQUEUE	4
141
142/*
143 * return values from elevator_may_queue_fn
144 */
145enum {
146	ELV_MQUEUE_MAY,
147	ELV_MQUEUE_NO,
148	ELV_MQUEUE_MUST,
149};
150
151#define rq_end_sector(rq)	((rq)->sector + (rq)->nr_sectors)
152
153#endif
154